Jacek Dziarmaga (27.02, 12:30)
Affiliation: Jagiellonian University, Poland Title: Determining topological order from infinite projected entangled pair states Abstract:A unique ground state of an infinite strongly correlated two-dimensional system can be efficiently computed with a tensor network known as an infinite projected entangled pair state (iPEPS). When the iPEPS is wrapped on an infinite torus it becomes a superposition of degenerate ground states. With infinite matrix product operators (MPO) we construct projectors on ground states with a definite anyon flux in each direction. The construction is repeated for three different tori related by modular transformations. Infinite MPO's are employed again for an efficient computation of overlaps between all the different ground states. From the overlaps we obtain the topological matrices $S$ and $T$ determining the topological order. The algorithm is tested on the toric code and the double semion model. It is shown to be robust against a perturbation driving them across a phase transition to a ferromagnetic order. It is also tested on a numerically optimized ground state of the Kitaev model.